This invention relates generally to compressors, and more particularly to a removable discharge port plate for a positive-displacement, rotary type compressor, such as a rotary-screw compressor, for example.
Typically, housing structures for rotary compressors are manufactured using metal casting methods. These housing structures include a one piece rear housing portion which has cast therein an axial discharge port and a radial discharge port. Previously, the axial discharge port has been sized to accommodate a range of built-in volume ratios. However, a single sized axial discharge port fails to optimize rotary compressor efficiency throughout the range of built-in volume ratios.
The placement of an axial discharge port in a rear compressor housing and the shape of the discharge port are critical for optimizing efficiency in a rotary-screw compressor. However, manufacturing a rear compressor housing by metal casting is not an exact procedure. For example, a core shift may occur in a rear housing mold during the casting process which may cause the axial discharge port to be improperly positioned in the rear housing. Additionally, a defect in the casting process may cause an axial discharge port to be misshaped. In such cases of defective casting, the rear compressor housings must be scraped. Therefore, defective casting causes material waste.
Stepped bores, which receive bearings and rotor shafts, are machined into the rear housing. Presently, two bores of differing diameters must be separately machined into the rear housing. This manufacturing process increases the cost and time necessary to manufacture the rear bearing housing.
During the operating life of a rotary compressor, a rotor may fail causing the cast-in axial discharge port and end face of a rear compressor housing to be scored or otherwise damaged. In such instances, the entire rear compressor housing is scraped to repair the compressor. This, of course, results in material waste.
The foregoing illustrates limitations known to exist in present compressors. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.